Gymnochthebius pluvipennis, Perkins, 2005

Perkins, Philip D., 2005, A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea, Zootaxa 1024 (1), pp. 1-161 : 1-161

Gymnochthebius pluvipennis new species

(Figures 68, 69,87)

Type Material. Holotype (male): Australia: South Australia: Warburton River , 1 km N White Bull Yard Kalamurina Stn., 27° 52' S, 137° 54' E, 6 October 1999, WHC exped. Deposited in the SAMA . Paratypes: Same data as holotype (10 SAMA). Representative specimens to be deposited in ANIC, MCZ and NPC .

Differential Diagnosis. A distinctive, markedly punctate species (Fig. 68) differing from all others by the combination of non­serial elytral punctation, each puncture with a short, slightly widened seta, the relatively flat elytral disc, the subrugulose pronotum, and the strongly densely punctate metasternal tabella. The form of the male genitalia also separates this species from all others in the genus (Fig. 69).

Description. Size (length/width, mm) holotype: body (length to elytral apices) 1.60/ 0.67; head 0.30/0.41; pronotum 0.41/0.52; elytra 1.04/0.67. Form moderately ovate, mod­ erately convex. Color dark brown, dorsum dull, with short, basally widened, distinctive setae.

Head with dorsum clothed in short decumbent setae; frons coarsely densely punctate; interocular foveae deep; interocular tuberculi indistinct; basomedial fovea broadly confluent with interocular foveae. Frontoclypeal suture deeply impressed, bisinuate. Clypeus midlength about 0.5 apical width, moderately coarsely punctate. Labroclypeal suture straight in dorsal view, evenly arcuate in anterior view. Labrum width 3x length, anterior margin without apicomedian tooth. Maxillary palpomere 3 twice length of 4.

Pronotum lateral hyaline border well developed, origin at base of lateral depression, weakly arcuate to posterior angles, very narrow around posterior margin; anterior margin of pronotum arcuate between lateral depressions; each lateral depression with posterior angle rounded, lateral margin sinuate, with sparse short setae; lateral fossulae very deep, terminating anteriorly in pit; pronotal disc convex, subrugose, punctures small, very dense, each with cuticular point at base of distinctive very short seta which contrasts with dark cuticle; median groove deep and moderately wide, ended before margins, tapering at ends; anterior foveae well developed; posterior foveae oblique, linear impressions as long as and about as deep as and slightly wider than median groove; posterolateral angles lacking impressions.

Elytra subrugose, flat on disc, sutural margin raised; punctures random, dense, each with cuticular point at base of distinctive, short, basally widened, decumbent seta; summit of declivity near posterior 0.66; elytral explanate margin narrow, lacking fringe of setae.

Metasternal glabrous area length less than width (as 15:23), flat, tabelliform, subrhomboidal, anteriorly attaining intercoxal process, strongly densely punctate. Abdominal sternites 1–2 and basal part of 3 with hydrofuge pubescence.

Aedeagus (Fig. 69): Length of main­piece 0.32 mm, parameres very slightly longer; lobes long, barbed, weakly arcuate between apex and barb; duct gradually narrowing apically; paramere seta very short.

Females have the explanate elytral margin slightly wider than in males; the labrum anterior margin is arcuate.

Etymology. Named in reference to the raindrop­like pattern of the elytral setae.

Distribution. Currently known only from the type locality in South Australia (Fig. 87).